Into the loudness blue yonder for Sky6 March 2014
UK broadcasters, facilities and production companies are coming to terms with R128 loudness control in the DPP specifications. BSkyB has already implemented the standard and, as senior sound supervisor Martin Black explains, change is good but not instantaneous.
Implementing any type of standard is not always an immediate, blanket process. With loudness for television production, some broadcasters in the UK first took practical steps to monitor and control discrepancies in perceived volume between different types of programming in the late 1990s and early 2000s by using early algorithms and meters.
In 2008 the Broadcast Committee on Advertising Practice (BCAP) published guidance on mixing soundtracks for TV commercials. It recommended the use of loudness meters based on the ITU BS 1770 standard, introduced in 2006, but with the provision for facilities still using peak meters of mixing to PPM6. More recently the Digital Production Partnership (DPP), established to draw up specifications for delivering programmes to the main UK broadcasters included loudness requirements using EBU R128 in its standards published in October 2013.
The aim is to make loudness control mandatory in October this year when UK broadcasters either move fully to file-based operations or begin the transition. Right now some still work to PPM6, while others, such as BSkyB, are using R128. Martin Black, a senior sound supervisor working at the broadcaster’s Studio centre in west London, took part in meetings held by PLOUD, the EBU working group that developed R128, and acknowledges the recommendation took some time to agree and compile, partly because loudness is a subjective issue.
“Right now we’re at the end of the beginning,” he comments about the implementation of R128. “That’s because it specifies only two parameters, so there will be further refinements made to it in the coming years.” He explains that elements to consider are true peak, which is in the standard; loudness range; short-term loudness; and momentary loudness. Another factor in this, he says, is the type of material being measured.
Most complaints about sound on TV tend to be about how loud they are, not just compared to other programmes but in general. Black observes that the other end of the scale can be just as problematic: “A current problem is what do we do with material that is intentionally quiet? If we normalise it that might bring it up to an unnaturally high level. But there is nothing to say it can’t be below the target of -23 LUFS [Loudness Unit, referenced to Full Scale] for a short period, when it could be -20 to -18. All it needs to be is no louder than the maximum.”
The initial thought is that the problem of something being too quiet would be exclusive to drama, where near or absolute silence can be used to create an atmosphere or tension. Black comments that it also applies to sports coverage, such as golf and cricket, where there is little or no background noise and periods without commentary.
Black adds that whether or not low levels are acceptable also depends on something out of the control of sound mixers and broadcasters – the threshold of audibility in viewers’ home when they’re watching TV. “That’s not often taken into consideration,” he says. “One of the biggest sources of complaints we get is about intelligibility but you can’t get round some parts of that, such as dialects. Loudness on its own doesn’t achieve intelligibility.”
Sky uses ##RTW TM7 and TM9 metering systems for live work and Tektronix versions of them in post-production. The Calrec Apollo consoles used at The Studios are fitted with #TFT bargraphs and while two PPMs are still available to mixers, Black says the intention is to “wean people off them”.
Fundamentally, though, the aim is not to change how mixing is done: “Rather than mix to the meter we’d like people to learn to work without it. For us the meter corroborates what the mixer’s ears are telling him or her to do.”
Martin Black concludes that there are still some problem areas, particularly with the junctions between programmes and commercials and the wider issue of different levels when changing channels. But, he says, especially when it comes to the area that was the target for loudness control – the commercials – things are getting better: “Now we’ve got the DPP spec for programme delivery, complaints about loudness are pretty much a thing of the past. It’s been a win for everybody.”